21320603 has 4 divisors (see below), whose sum is σ = 22442760. Its totient is φ = 20198448.

The previous prime is 21320581. The next prime is 21320639. The reversal of 21320603 is 30602312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21320603 - 2¹² = 21316507 is a prime.

It is a super-2 number, since 2×21320603² = 909136224567218, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21320683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 561050 + ... + 561087.

It is an arithmetic number, because the mean of its divisors is an integer number (5610690).

Almost surely, 2^21320603 is an apocalyptic number.

21320603 is a deficient number, since it is larger than the sum of its proper divisors (1122157).

21320603 is a wasteful number, since it uses less digits than its factorization.

21320603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1122156.

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21320603 is about 4617.4238488577. The cubic root of 21320603 is about 277.2893317624.

Adding to 21320603 its reverse (30602312), we get a palindrome (51922915).

The spelling of 21320603 in words is "twenty-one million, three hundred twenty thousand, six hundred three".